Determination of phage type, colicin type and plasmid profile in Shigella sonnei

Complex typing was carried out of 33 Shigella sonnei strains isolated in 1985 and 1986 One to six plasmids were carried by 32 strains typable by phages, whereas plasmid was not demonstrated in a phage-resistant strain. A 1.4 Md plasmid was carried by all strains. By determining the plasmid profile the clonal connection between the strains could be demonstrated. Strains assumed to be in clonal connection on the basis of phenotypic properties, were divided into subclones. Identical plasmid profile was observed among strains belonging to different phage and colicin types.